1. Field of the Invention
The present invention relates to SARS-CoV-specific B-cell epitopes and the epitope-based peptides, which can be applied to SARS diagnosis and have potentials to be the immunogens for producing antibodies against the SARS virus or for development of a SARS vaccine.
2. The Prior Arts
In Feb. 26, 2003, an American businessman was admitted to a hospital in Hanoi after falling ill while on a business trip to Vietnam. He died after transferring to Hong Kong for treatment. Since then, cases of atypical pneumonia combined with respiratory tract infections are reported in Hong Kong, Vietnam, Singapore, and Canada, respectively. The symptoms of this atypical pneumonia including diffuse pneumonia and respiratory failures are more serious than those of pneumonia caused by virus or bacteria. It was, therefore, named Severe Acute Respiratory Syndrome (SARS). WHO formally announced that the disease agent of SARS was identified as a SARS-associated coronavirus (SARS-CoV) on Apr. 16, 2003. This new strain of Corona virus is designated as SARS-CoV that has not been previously identified in humans or animals and cannot be excluded from mutant virus. What is known about SARS-CoV so far is that human beings have no antibody protection against the virus. The virus has a very strong infection rate, propagation ability, toxicity and pathogenicity which may cause lung fibrosis to the patient, even induce shortness of breath or life-threatening respiratory failure and result in death.
According to the case definitions by WHO (World Health Organization), which are revised on May 1, 2003, are shown in the following:
Suspect Case:    1. A person presenting after 1 Nov. 2002 with history of:            high fever (>38° C.)        AND        cough or breathing difficulty        AND one or more of the following exposures during the 10 days prior to onset of symptoms:        close contact with a person who is a suspect or probable case of SARS;        history of travel, to an area with recent local transmission of SARS        residing in an area with recent local transmission of SARS            2. A person with an unexplained acute respiratory illness resulting in death after 1 Nov. 2002, but on whom no autopsy has been performed            AND one or more of the following exposures during to 10 days prior to onset of symptoms:        close contact, with a person who is a suspect or probable case of SARS;        history of travel to an area with recent local transmission of SARS        residing in an area with recent local transmission of SARS        
Probable Case:    1. A suspect case with radiographic evidence of infiltrates consistent with pneumonia or respiratory distress syndrome (RDS) on chest X-ray (CXR).    2. A suspect case of SARS that is positive for SARS coronavirus by one or more assays.    3. A suspect case with autopsy findings consistent with the pathology of RDS without an identifiable cause.
The main symptoms of SARS include high fever (above 38° C.), dry cough, and shortness of breath or breathing difficulties. Changes in chest X-rays indicative of pneumonia also occur. SARS may be associated with other symptoms, including headache, muscular stiffness, and loss of appetite, malaise, confusion, rash and diarrhea. In most serious cases, the respiratory illness progresses to diffuse pneumonia, poor oxygen exchange, which causes lack of oxygen in lung and severe respiratory difficulty. The disease can progressively worsen and eventually result in death. The incubation period ranges from 2 to 7 days generally, and may get more than 10 days with the longest period and 3 to 5 days with the common period. It could extend to 14 days to allow an extra margin of safety.
Due to the long incubation period and the highly contagious characteristics of SARS-CoV, accurate and quick laboratory diagnostics are still not available and SARS diagnosis remains dependent on clinical findings. Therefore, many people are developing the technology for rapid detection of SARS. SARS diagnostic methods are mainly based on Polymerase Chain Reaction (PCR) technology up to now. When SARS-CoV RNA is detected by RT-PCR, at least two different clinical specimens (such as nasal swabs and stools), clinical specimens from the same portion but acquired at different dates (such as nasal swabs taken twice or more times), or an original specimen subjected to two respective different assays or repeated PCR. Although detection of SARS-CoV can be accomplished through PCR, this technology has several limitations. It may take several days to confirm the SARS-CoV from patient samples. The labor requirements and capital resources are large and the cost is not low enough for large-scale screening.
In early stage of the disease, the SARS patients are offered with supportive treatments to prevent the deterioration of the disease. Active treatments are offered for those developed early symptoms after close contact with SARS patients (short incubation period), the weak elderly, the small child, or patients accompanied with other diseases.
Treatments of SARS include antiviral medications (such as oseltamivir or ribavirin) and antibiotics (to prevent bacterial infection as well) since onset of SARS symptoms within 5 days (the early stage). However, no medication has been proven to cure SARS so far. A rapid diagnostic test that can reliably diagnose SARS-CoV infection during the early phase of illness, which is easy to manipulate, labor-saving and cost-effective, as well as an effective treatment drugs, are the key issues needed to prevent the spread of SARS.